Through a psychic rapport with his half-brother Kyrano, The Hood learns that International Rescue is ready to begin operations. Plotting to lure the International Rescue craft, he straps a bomb to the landing gear of the atomic-powered airliner Fireflash on its maiden flight from London to Tokyo so that if the crew attempts a landing by conventional means, the bomb will detonate. Although the airliner's atomic motors enable the Fireflash to stay in the air for six months, the passengers and crew will receive fatal doses of radiation when the anti-radiation shield on the reactor fails. On board is Kyrano's daughter Tin-Tin, en route to Tracy Island to join International Rescue. The Fireflash crew attempt to dislodge the bomb with aerobatics, without success. Then an attempt is made to winch a man to the landing gear from a TX 204 target-carrying aircraft, but this also fails, so Jeff dispatches Scott and Virgil in Thunderbirds 1 and 2 to London Airport. International Rescue are in business!

NotesThis episode has no on-screen title but is referred to in all production documentation by the title of the shooting script - Trapped In The Sky. The arrangement of the music on the main titles and end credit sequences is unique to this episode and sound effects are heard in the episode montage during the opening titles. Alan is voiced by Ray Barrett as Matt Zimmerman had not been employed when the dialogue recording session took place. A short piece of Barry Gray's 'Formula Five' track, composed and recorded for Fireball XL5, can be heard on the monitors in Thunderbird 5.

Air Terrainean's Lieutenant Meddings is named after Thunderbirds visual effects supervisor Derek Meddings. Fireflash is the only non-International Rescue vehicle to appear in the series' end titles. The airliner is seen again in Operation Crash-Dive, The Impostors, The Man From MI.5, The Duchess Assignment and Security Hazard. Commander Norman makes further appearances in Operation Crash-Dive, Edge Of Impact, Security Hazard and Alias Mr. Hackenbacker, while Captain Hanson is seen again in Operation Crash-Dive, The Impostors, The Duchess Assignment and Security Hazard.

Trapped In The Sky was adapted for audio on the Century 21 Mini-Album Thunderbird 1 (MA 108, 1966) narrated by Shane Rimmer as Scott Tracy. This adaptation was re-released on the Century 21 LP International Rescue (LA 3, 1966) and issued in electronically created stereo on the Hallmark/Marble Arch Records LP Thunderbirds & Captain Scarlet (HMA 227, 1967). It was re-released on the Marble Arch LP TV Favourites Vol. 2 (MAL 771, 1968) and then issued on cassette as part of PolyGram's Thunderbirds audiobook collection (514 385-4, 1992). With a new introduction by Gerry Anderson, this audio adaptation was first broadcast on BBC Radio 5 at 8.05pm on November 5th, 1990. Trapped In The Sky was adapted for audio again on Penguin Audiobooks' Thunderbirds - 1 (ISBN 0141803355, 2001) audiocassette collection with additional narration by William Roberts.

Oops!Several shots from beneath Thunderbird 1 show the 'T' of 'Thunderbird' painted on the nose cone, yet the nose cone is free of markings in all other shots of the craft. At the end of the episode, Operation Cover-Up replaces the portraits of the brothers in uniform with pictures of them in civilian clothing, but when the doctor enters the room, the uniformed portraits are still clearly visible in shots of Scott, Gordon and Jeff.

In the African jungle, the US Army is testing a new all-terrain Sidewinder vehicle when the ground gives way and it falls into a blazing pit with a three man crew trapped inside - 300 feet below ground. Lieutenant Mead, a member of the relief crew, is lowered into the pit from a helijet to assess the situation; he is badly burned but able to report the condition of the vehicle. A second man, Sergeant Reynolds, tries to attach a line to one of the Sidewinder's legs to haul it upright, but he too is badly burned and the line slips off during the attempt. General Peters calls in International Rescue and Scott, Virgil and Brains are soon speeding to the scene in Thunderbirds 1 and 2. Thunderbird 1's remote camera reveals that the pit was once an open-cast mine used as a military equipment dump after World War II. A crust of earth has formed over the top and the International Rescue team realise that they must remove the remainder of the crust before the 500-ton Sidewinder can be dragged up the side of the pit...

NotesPit Of Peril features the smallest number of regular characters seen in any Thunderbirds episode and no female characters whatsoever. The episode introduces the Mole which is later seen in City Of Fire, Cry Wolf and The Duchess Assignment>. The vehicle also appears for the first time in the end title sequence, having been absent from the end titles of Trapped In The Sky. The Thunderbird 1 Remote Camera is used again in Edge Of Impact. Colonel Sweeney previously appeared as Fireflash pilot Captain Hanson in Trapped In The Sky and one of his subordinates was Hanson's co-pilot in that episode.

Pit Of Peril was adapted as a comic strip by Alan Fennell and Steve Kyte for Thunderbirds: The Comic (issues 4-5, 1991). The episode was also adapted for audio on Penguin Audiobooks' Thunderbirds - 1 (ISBN 0141803355, 2001) audiocassette collection with additional narration by William Roberts.

Oops!When the Mole returns to the surface with Scott and Virgil on board, dust and sand can be seen pouring up from the ground onto the Mole's tracks (footage of the Mole tunnelling into the ground has simply been reversed). Thunderbird 1 sets fire to a dead tree trunk when Scott lifts off at the end of the episode.

A car crash in the underground parking lot of the newly opened Thompson Tower maxi-mall causes a raging inferno which soon consumes the building when the sprinkler system fails. Unseen by the security cameras, the Carter family - Joe, Blanche and their son Tommy - is trapped by sealed fire doors in the access corridors beneath the Tower. By the time that they are spotted, it is too late to effect a rescue by normal means. The Tower Controller calls International Rescue and Scott and Virgil race to the scene in Thunderbirds 1 and 2, despite having only just recovered from the side-effects of experiments with new cutting equipment fuelled by oxyhydnite gas. As Thunderbird 1 arrives, the Tower collapses, raising doubts as to how long the ceiling of the underground corridor can last before caving in. Scott and Virgil realise that the only way to reach the Carters in time is to cut through the fire doors with the oxyhydnite equipment, whatever the risks from the side-effects...

NotesThe Thompson Tower has 350 floors on which every single commercial item produced throughout the entire world can be obtained. Half a mile wide and two miles deep, the Tower houses 12 hotels and features a massive sub-basement with parking for 10,000 vehicles linked to the store by a monorail four miles long.

This episode introduces the Firefly which is seen again in Terror In New York City and Cry Wolf. The Tracy brothers are also seen using their hoverbikes (the Thunderbirds equivalent of Fireball XL5's jetmobiles and Stingray's monocopters) for the first time. The vehicles also come in handy during Vault Of Death, Martian Invasion, Cry Wolf and Attack Of The Alligators!

City Of Fire was adapted as a comic strip by Alan Fennell and Keith Watson for Thunderbirds: The Comic (issues 15-17, 1992), and collected in the graphic album Thunderbirds: Shock Wave (Ravette Books, 1992).

Oops!Although the Thompson Tower is clearly situated in the United States, a sign on the wall of the Control Centre uses the British spelling of 'Centre' instead of the American 'Center'.

The Sun Probe, a rocket designed to ferry three solarnauts to the Sun and return with a piece of solar matter, is launched from Cape Kennedy and within a week has arrived at its destination. The mission goes according to plan but as the solarnauts prepare to return to Earth, high radiation levels prevent Sun Probe's control systems from firing the retro rockets and the solarnauts find themselves on a collision course with the Sun. Brains realises that a powerful radio beam is needed to fire Sun Probe's retros and Jeff decides to mount a two-pronged rescue: Thunderbird 3, with Alan, Scott and Tin-Tin on board, is launched into space whilst Virgil and Brains head for Mount Arkan in Thunderbird 2 with a powerful mobile transmitter. But Alan's first attempt to reach Sun Probe with the safety beam fails and he and Scott realise that Thunderbird 3 must go much closer to the Sun than originally planned...

NotesJeff states that this is Tin-Tin's first mission and the episode also marks the first appearance of Brains's robot Braman, who is later seen in Edge Of Impact and The Cham-Cham. Although we do not see Grandma, Jeff tells Virgil that she will organise auxiliary clothing for the trip to Mount Arkan, implying that his mother is already living on Tracy Island (see Move - And You're Dead).

Sun Probe was adapted for audio on the Century 21 Mini-Album Thunderbird 3 (MA 112, 1966) narrated by Matt Zimmerman as Alan Tracy. This adaptation was later issued on cassette as part of PolyGram's Thunderbirds audiobook collection (514 385-4, 1992). With a new introduction by Gerry Anderson, the audio adaptation was first broadcast on BBC Radio 5 at 8.05pm on November 19th, 1990. The episode was also adapted as a comic strip by Alan Fennell and Malcolm Stokes for Thunderbirds: The Comic (issues 6-8, 1991/92)

Oops!During the television report about the Sun Probe, a diagram shows the solarnauts' control cabin within the Probe Module, but the control cabin is within the body of the Probe Rocket when the Module is fired into the solar prominence. Alan and Scott manage to swap seats during their journey to Thunderbird 3 on the sofa, but are in their original positions when the sofa arrives on board the spacecraft. When Thunderbird 2 leaves the hangar on Tracy Island, it appears that Pod 3 has been selected (Pod 2 is visible to the right of Thunderbird 2), yet when Virgil and Brains arrive at Mount Arkan, the Transmitter Truck emerges from Pod 6. (The same continuity error also occurs in Vault Of Death, Move - And You're Dead, Martian Invasion, The Perils Of Penelope and Day Of Disaster.)

As Scott returns from the scene of a fire in Tokyo, Thunderbird 1 is shot down in the Sahara Desert by three unidentified fighter planes. Scott cracks his head as Thunderbird 1 crashes into the sand dunes, but he is able to open the cabin hatch before passing out. He is found by two archaeologists, Wilson and Lindsey, who administer first aid. They radio International Rescue and Virgil, Brains and Tin-Tin soon arrive in Thunderbird 2. After the International Rescue group return to Tracy Island, the archaeologists continue their search for the lost pyramid of Khamandides, but their supplies trailer breaks loose from their jeep and explodes, leaving the pair stranded without water. Their SOS call is picked up by Alan on Thunderbird 5 and Scott is soon on his way in Thunderbird 1. Meanwhile, Wilson and Lindsey discover the pyramid of Khamandides but the door through which they enter the pyramid swings shut behind them, trapping them inside!

NotesThe working title of this episode was 'Desert Of Danger'. Although the pyramid people are named as 'Zombites' in the script and the symbol on their helmets is a stylised 'Z', they are never actually referred to as 'Zombites' in the episode. For the mission to rescue Scott, Tin-Tin wears the same blue uniform that she was seen in on board Thunderbird 3 in Sun Probe - this is presumably the female equivalent of the Tracy brothers' International Rescue uniforms. John's dialogue indicates that Scott occasionally takes turns at manning Thunderbird 5.

The Zombites' jet fighters are adapted and re-sprayed WASP aircraft from Stingray. The explorers' jeep later becomes The Hood's jeep in The Mighty Atom, Martian Invasion and Cry Wolf.

The Uninvited was adapted as a comic strip by Alan Fennell and Steve Kyte for Thunderbirds: The Comic (issues 12-14, 1992) and collected in the graphic album Thunderbirds: Shock Wave (Ravette Books, 1992).

Oops!When Tin-Tin responds to news of Scott's disappearance, a floor puppeteer's hand (with dirty fingernails!) can be seen in the bottom of the screen lifting Tin-Tin from her seat. Between arriving on board Thunderbird 3 and climbing into the elevator to travel up to the control room, Alan completely changes his clothes from a purple suit to green checked shirt and beige trousers. Similarly, Scott returns from Thunderbird 3 wearing different clothes from those that he left in, swapping a yellow suit and orange shirt for his usual blue roll-neck and checked jacket. The symbols on the walls of the Zombites' control room are the reverse of the symbol on their helmets.